This invention relates to a technology for displaying a picture using various kinds of electro-optical elements, such as a liquid crystal and an OLED (Organic Light-Emitting Diode) element.
An electro-optical device, such as a liquid crystal device, has a plurality of pixels arranged on the surface of a substrate having an insulating property, and a driving circuit for supplying a driving signal to these pixels. Further, a structure has been proposed where a transistor constituting a driving circuit is formed on the surface of a substrate by SOI (Silicon On Insulator) technology. This kind of electro-optical device is called a driver built-in type electro-optical device, and has various advantages such as reduced manufacture cost, compared to the electro-optical device whose IC chip including a driving circuit is mounted on the substrate. In a driver built-in type electro-optical device, a polysilicon layer is employed as a semiconductor layer for each transistor constituting a driving circuit.